The treatment of mycosis fungoides involves the use of large beams of nominally 6 MeV electrons. The irregular shape of the human body and especially the complicated shapes of hands and feet make dosimetry according to the usual standards of uniformity difficult. Especially hands and feet require shielding over a large part of the course, by cumbersome and uncomfortable means. An investigation has been started into the use of a "sieve" technique which would allow decreasing the intensity locally, without affecting the energy, that is the penetrating power, in a controlled manner. This would reduce the discomfort of the patients greatly.